On Linux servers, you could set permissions to the various folders inside your web account. When your files and folders are on the web, it si accessable by everyone, and for certain secure folders, you might want to give it read only permissions, since you could allow people to read from the files, and not write to them.

Chmod is a permission with which you can do various combinations of permissions to a file or a folder on the server, ranging from 000 to 777